JPH03114912A - Suspension device of automobile - Google Patents

Abstract

PURPOSE:To improve running stability at the time of backward-driving for an active suspension device composed of a hydraulic shock absorber and spring, by discriminating either forward- or backward-driving, by changing over to a forward-driving suspension characteristic at the time of forward-driving, and by changing over to a backward-driving suspension characteristic at the time of backward-driving. CONSTITUTION:When it is discriminated by a progressing direction discriminating means 1 that a car is in a state of forward-driving, car speed and a handle steering angle are read by a characteristic changing means 2, so as to determine a lateral Gs, based on which control of forward-driving suspension characteristic is performed, as well as riding feeling emphasizing control, normal- or reverse- rolling control, and navigation stability control. At the time of backward-driving, backward-driving control is carried out in such a way that an aimed rolling angle is specified as zero, while speed of displacement is specified, for example, as 0.03 in a backward-driving suspension characteristic, so as to prohibit normal rolling or reverse rolling, and position displacement is thus suppressed. In this structure, navigation stability at the time of backward-driving can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a suspension device for a vehicle.

(Prior art and its problems) A vehicle suspension, generally called a passive suspension, has a damper unit consisting of a hydraulic damper and a spring (generally a coil spring), and has preset characteristics of the damper unit. Suspension characteristics are uniformly set. Of course, it is also possible to make the damping force of the hydraulic damper variable, but this does not significantly change the suspension characteristics.

On the other hand, recently, so-called active suspensions have been proposed in which suspension characteristics can be changed arbitrarily.Active suspensions basically consist of a combination of sprung weight and unsprung weight. A cylinder device is installed between them, and the suspension characteristics are controlled by controlling the supply and discharge of hydraulic fluid to the cylinder device (see Japanese Patent Publication No. 14365/1983).

In other words, in this active suspension,
Depending on the running state of the vehicle, suspension characteristics can be changed significantly for hard, soft, attitude control, roll control during turning, and the like.

Incidentally, the driving characteristics of the vehicle, such as yawing, are significantly different between forward movement and backward movement. Furthermore, the driver's driving posture is significantly different, such as having to look behind the vehicle when reversing.

However, when predetermined suspension characteristics are imparted to the active suspension, those suspension characteristics will be exhibited regardless of whether the vehicle is moving forward or backward.

For example, when a soft suspension characteristic, that is, a characteristic that weakens the convergence of vertical movement, occurs when reversing, it becomes difficult to maintain a constant line of sight.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a suspension device for a vehicle that can ensure running stability, especially when reversing, in an active suspension.

(Means and operations for solving the problems) In order to achieve the above object, the present invention has the following configuration. In other words, it is assumed that the suspension system is for a vehicle in which a cylinder device is installed between unsprung weights and unsprung weights, and the supply and discharge of hydraulic fluid to the cylinder devices is controlled based on preset conditions. As shown in FIG. 8, there is a traveling direction determining means for determining whether the vehicle is moving forward or backward; and upon receiving a signal from the traveling direction determining means, when the vehicle is moving forward, the suspension characteristic for forward movement is applied. and a characteristic changing means for switching to the suspension characteristic for reversing when the vehicle is moving backward.

With the above configuration, it is possible to provide suspension characteristics that are desirable for forward movement, and to provide suspension characteristics that are desirable for backward movement. For example, when reversing suspension characteristics are set to be hard or to reduce the target roll angle of roll control, it becomes possible to reduce posture changes during reversing, and it is possible to suppress changes in the driver's line of sight.

(Effects of the Invention) As is clear from the above description, according to the present invention, it is possible to provide suspension characteristics that are desirable for each of forward and reverse driving, thereby improving driving stability especially when reversing. can.

(The following is a blank space) (Example) An example of the present invention will be described below based on the attached drawings. In addition, the code rFJ used with numbers in the following explanation is for the front wheel, rRJ is for the rear wheel, rFRJ is for the right front wheel, rFLJ is for the left front wheel, rRRJ is for the right rear wheel, and "RL" is for the right rear wheel.
means for the left rear wheel, and therefore, when there is no particular need to distinguish between them, the description will be made without using these identification symbols.

1 Indigo Dan 1 In Figure 1, 1 (IFR, IFL, 188%
IRL) is a cylinder device provided for each front, rear, left and right wheel, and these include a cylinder 2 connected to the unsprung weight, and a piston rod 3 extending from inside the cylinder 2 and connected to the unsprung weight. and has. Inside cylinder 2,
A liquid chamber 5 is defined above the piston rod 3 by the piston 4, which is integral with the piston rod 3, and the liquid chamber 5 and the lower chamber are in communication with each other. As a result, when hydraulic fluid is supplied to the fluid chamber 5, the piston rod 3 extends and the vehicle height increases.
Furthermore, when the hydraulic fluid is discharged from the fluid chamber 5, the vehicle height becomes lower.

For the liquid chamber 5 of each cylinder device 1, a gas spring 6 (
6FR16FL, 6RR16RL) are connected.

Each of the gas springs 6 is composed of four cylindrical springs 7 having a small diameter, and the cylindrical springs 7 are connected to the liquid chamber 5 through an orifice 8 in parallel to each other.

Of these four cylindrical springs 7, except for one, the remaining three are connected to the liquid chamber 5 via a switching valve 9. As a result, when the switching valve 9 is in the switching position as shown, the four cylindrical springs 7 are communicated only through the orifice 8, and the damping force at this time is small. Furthermore, when the switching valve 9 is switched from the illustrated position, the three cylindrical springs 7 are also communicated with the liquid chamber 5 through the orifice 10 built into the switching valve 9, resulting in a large damping force. Become something. Of course, by changing the switching position of the switching valve 9, the spring characteristics of the gas spring 6 are also changed. This suspension characteristic can also be changed by changing the amount of hydraulic fluid supplied to the fluid chamber 5 of the cylinder device 1.

In the figure, 1) is a pump driven by an engine, and high-pressure hydraulic fluid pumped up by pump 1) from a reservoir tank 12 is discharged into a common passage 13.

The common passage 13 is branched into a front passage 14F and a rear passage 14R, and the front passage 14F is further divided into a right front passage 14F.
R and a left front passage 14FL. The front right passage 14FR is connected to the liquid chamber 5 of the front right wheel cylinder device IFH, and the front left passage 14FL is connected to the liquid chamber 5 of the front left wheel cylinder device IFL. A supply flow rate control valve 15FR and a pilot valve 16FR as a delay valve are connected to this front right passage 14FH from the upstream side thereof. Similarly, a supply flow control valve 15FL and a pilot valve 16FL are connected to the left front passage 14FL from its upstream side.

A first relief passage 17FR for the right front passage is connected to the front right passage 14FH from between both valves 15FR and 16FR, and this first relief passage 17FR finally passes through the front wheel relief passage 18F to the reservoir tank 12. It is connected to A discharge flow rate control valve 19FR is connected to the first relief passage 17FH. Moreover, the passage 14FR downstream of the pilot valve 16FR is connected to the first relief passage 17FH via the second relief passage 20FR, and the relief valve 21FR is connected to this. Furthermore, a filter 29FR is interposed in the passage 14FH closest to the cylinder device IFR. This filter 29FR
is the cylinder device IFR and the valve 1 located closest to it.
Located between 6FR121FR and the cylinder device IFR
Abrasion powder generated from the valve 16 due to sliding etc.
Prevents it from flowing to the FR121FR side.

Note that the passage configuration for the left front wheel is also configured in the same manner as the passage configuration for the right front wheel, so a redundant explanation thereof will be omitted.

A main accumulator 22 is connected to the common passage 13, and an accumulator 23F is also connected to the front wheel relief passage 18F. This main accumulator 22 serves as a pressure accumulation source for hydraulic fluid together with a sub-accumulator 24 to be described later, and is intended to prevent the amount of hydraulic fluid supplied to the cylinder device 1 from becoming insufficient. Further, the accumulator 23F is provided to prevent the high-pressure hydraulic fluid in the front wheel cylinder device 1 from being suddenly discharged to the low-pressure reservoir tank 12, that is, to prevent the water hammer phenomenon.

The hydraulic fluid supply/discharge passage for the rear wheel cylinder device IRR1IRL is also configured in the same manner as for the front wheels, so a redundant explanation thereof will be omitted. However, there is no equivalent to the pilot valve 21FR121FL in the rear wheel passage.
In addition, the main accumulator 22 is located in the rear wheel passage 14R.
A sub-accumulator 24 is provided in consideration of the fact that the passage length from the front wheel is longer than that for the front wheel.

The common passage 13, that is, each passage 14F% for front and rear wheels
14R is connected to the front wheel relief passage 18F via the relief passage 25, and the relief passage 25 includes:
A control valve 26 consisting of an electromagnetic on-off valve is connected.

In FIG. 1, 27 is a filter, and 28 is a pressure regulating valve as a pressure accumulation control means for adjusting the discharge pressure from the pump 1), that is, the pressure accumulated in the accumulator 22, to be within a predetermined range. In the embodiment, the pressure valve 28 is configured as a variable displacement swash plate piston type pump 1) and is integrated into the pump 1) (discharge pressure 120 to 160 kg/am2).

The pilot valve 16 is opened and closed depending on the pressure difference between the pressure in the front and rear passages 14F or 14R1, that is, the common passage 13, and the pressure on the cylinder device I side. Therefore, for the pilot valves 16FR and 16FL for the front wheels, a common pilot passage 31F branched from the passage 14F is led out, and two branches branched from the common pilot passage 31F.
Among the main branch pilot passages, one passage 31FR is connected to the pilot valve 16FH, and the other passage 3IFL is connected to the pilot valve 16FH.
is connected to the pilot valve 16FL.

An orifice 32F is provided in the common pilot passage 31F. Note that the pilot passage for the rear wheels is similarly configured.

Each of the pilot valves 16 is constructed, for example, as shown in FIG. 2, and the one shown is for the right front wheel circumference. This pilot valve 16 has, in its casing 33,
A main channel 34 forming a part of the passage 14FH is formed,
A passage 14FR is connected to the main passage 34. A valve seat 35 is formed in the middle of the main flow path 34, and the opening/closing piston 36, which is slidably inserted into the casing 33, is seated on and off the valve seat 35, so that the pilot valve 1
6FR is opened and closed.

The opening/closing piston 36 is integrated with a control piston 38 via a valve shaft 37. This control piston 38 is
It is slidably inserted into the casing 33 to define a liquid chamber 39 within the casing 33, and the liquid chamber 39 is connected to the branch pilot passage 31FR via a control flow path 40. .

The control piston 36 is then operated by a return spring 41.
As a result, the opening/closing piston 36 is biased in the direction in which it is seated on the valve seat 35', that is, in the direction in which the pilot valve 16FR is closed. Furthermore, the control piston 38 has a communication port 42.
The pressure of the main flow channel 34 is applied on the side opposite the liquid chamber 39 via. As a result, the pressure in the liquid chamber 39 (on the common passage 13 side) is reduced in the main passage 34 (in the cylinder device IFR
When the pressure becomes 1/4 or less of the pressure on the side), the opening/closing piston 36 seats on the valve seat 35 and the pilot valve 16FR is closed.

Here, from the state where the pilot valve 16FR is open,
When the pressure on the common passage 13 side increases (decreases), this pressure decrease is delayed by the action of the orifice 32F, and the pressure decreases in the liquid chamber 39.
Therefore, the pilot valve 16FR is closed after a delay from the pressure drop (in the embodiment, this delay time is set to about 1 second).

Next, the effect of the multiple valves mentioned above will be explained.

■Switching valve 9 In the embodiment, the switching valve 9 is operated to increase the damping force only during turning.

■Relief valve 21 The relief valve 21 is normally closed and the cylinder device 1
side pressure is above a predetermined value (160 to 200 k in the example)
g/cm'), it opens.

In other words, it serves as a safety valve that prevents the pressure on the cylinder device l side from rising abnormally.

Of course, the relief valve 21 is a cylinder device IRR for the rear wheels.
Although it can also be provided for 1 IRL, in the example, it is assumed that the vehicle has a weight distribution set to be considerably larger on the front side than on the rear side, so that the pressure on the rear wheel side is equal to the pressure on the front wheel side. The relief valve 21 is not provided on the rear wheel side in consideration of the fact that it does not become larger than the above.

(2) Flow rate control valves 15.19 Both the supply and discharge flow rate control valves 15.19 are electromagnetic spool valves that can be switched between an open state and a closed state as appropriate. However, when it is open, it has a differential pressure adjustment function that keeps the differential pressure between the upstream and downstream sides almost constant (due to flow rate control, this differential pressure must be kept constant). ). More specifically, the displacement position or opening degree of the spool of the flow control valve 15.19 is changed in proportion to the supplied current, and this supplied current is determined based on a flow rate-current correspondence map created and stored in advance. Determined based on That is, the supplied current corresponds to the required flow rate at that time.

By controlling the flow rate control valves 15 and 19, the supply and discharge of hydraulic fluid to the cylinder device 1 are controlled, thereby controlling the suspension characteristics.

In addition to this, when the ignition is OFF, this O
For a predetermined period of time (2 minutes in the embodiment) from the time of FF, only the control in the direction of lowering the vehicle height is performed. In other words, it takes into account changes in the payload caused by getting off the vehicle, etc., and prevents the vehicle height from becoming partially high (maintaining the standard vehicle height).
.

■Control Valve 26 The control valve 26 is normally closed by being energized, and is opened in the event of a failure. This failure can occur, for example, if part of the flow control valve 15 or 19 becomes stuck, if the sensors described below fail, if the hydraulic pressure of the hydraulic fluid fails, or if the pump 1) fails. There are cases where

In addition, in the embodiment, the control valve 26 is opened after a predetermined period of time (for example, 2 minutes) has elapsed since the ignition was turned off.

Note that when this control valve 26 opens, the pilot valve 1
6 is closed later as described above.

■Pilot valve 16 As already mentioned, the pilot valve 16 is opened with a delay after the pressure in the common passage 13 decreases due to the action of the orifices 32F and 32H. For example, in the event of a failure in which a part of the flow rate control valve 15 remains open, the pilot pressure decreases due to the opening operation of the control valve 26, which causes the passage 14FR-14R to
L is closed to confine the hydraulic fluid in the cylinder devices IFR-IRL, and the vehicle height is maintained. Of course, at this time,
The suspension characteristics are fixed to so-called passive characteristics.

Figure 3 shows the control system of the hydraulic fluid circuit shown in Figure 1. In this Fig. 3, WFR is the right front wheel, WF
L is the left front wheel, WRR is the right rear wheel, WRL is the left rear wheel,
U is a control unit configured using a microcomputer. This control unit U includes each sensor or switch 5IFR to 51RL, 52FR to 52RL,
Signals from 53FR153FL, 53R and 61-65 are input. In addition, from the control unit U, the switching valve 9
, the flow control valve 15 (15FR to 15RL), 19
(19FR to 19RL) are output to the control valve 26.

The sensors 51FR to 51RL are connected to each cylinder device IF.
It is provided at R to IRL to detect the amount of extension, that is, the vehicle height at each wheel position. Sensor 52FR~5
2RL detects the pressure in the liquid chamber 5 of each cylinder device IFR to IRL (see also FIG. 1). sensor 5
3FR153FL and 53R are G sensors that detect acceleration in the vertical direction. However, on the front side of vehicle B, two G sensors 53FR1 are installed at almost left-symmetric positions on the front axle.
53FL, but at the rear of the vehicle B, only one G sensor 53R is provided at the middle position between the left and right sides on the rear axle. In this way, one virtual plane representing the vehicle body B is defined by the three G sensors, and this virtual plane is set to be a substantially horizontal plane.

The sensor 61 detects vehicle speed. Above sensor 6
Reference numeral 2 detects the operation of the steering wheel, that is, the steering angle.

The control unit U basically performs active control conceptually shown in FIG. 4, that is, in the embodiment, vehicle attitude control (vehicle height signal control), ride comfort control (vertical acceleration signal control), and vehicle control. torsion control (pressure signal control).

The results of these multiple controls are finally expressed as the flow rate of the hydraulic fluid flowing through the flow rate control valves 15 and 19 as flow rate adjusting means.

Next, an example of how to control the suspension characteristics based on the output of each sensor will be described with reference to FIGS. 4 and 5.

The content of this control can be roughly divided into the most basic attitude control of the vehicle body B based on the output of the vehicle height sensor, ride comfort control based on the output of the G sensor, and torsion suppression control of the vehicle body B based on the output of the pressure sensor. Since then, it has been divided into the following sections.

■Attitude control (vehicle height sensor signal control) This control consists of three attitude controls that suppress bounce, pitch, and roll.
Feedback control is performed using PD sub-control (proportional-derivative control).

For each of these three attitude controls, how to handle the output from each vehicle height sensor is indicated by the "+" and "-" signs shown on the left side of the figure for each control section for bounce, pitch, and roll. This is shown by Furthermore, the "+" and "-" signs shown on the right side of each control section in the figure indicate that each control section controls posture changes. A code opposite to that shown on the left side of the center is given.

In other words, in bounce control, PD sub-control is performed in a direction in which the added value of each vehicle height on the left and right front sides and the added value of each vehicle height on the left and right rear sides match the reference vehicle height value, and the control formula used at this time is This is shown in the following equation (1).

KBl+ (Ta2・S/(1+TB2・S)) ・
, KH2... (1) KBI, KH2, Ta2: Control gain (constant) S: Operator Also, in pitch control, the left and right rear vehicle heights are added to the sum of the left and right front vehicle heights. PD sub-control is performed in the direction in which the subtracted value becomes zero. Furthermore, in roll control, the PD is adjusted in the direction in which the added value of each vehicle height on the left front and rear sides matches the added value of each vehicle height on the right front and rear sides (so that the target roll angle is achieved).
Sub-control.

Each of the control values obtained from the three PD sub-controls described above is obtained for each of the four cylinder devices l, and is added together for each control value for each cylinder device l, and finally the control values for the four attitude control The flow rate signals are determined as QXFR to QXRL.

Of course, for both the pitch control and roll control, the control equations for the PD sub-control are in the form of equation (1) above (however, the control gains are set for pitch control and roll control). .

(2) Riding comfort control (G sensor signal control) This riding comfort control is intended to prevent the deterioration of riding comfort caused by the attitude control in (2) above. Therefore, in response to the three attitude controls mentioned in (2) above, feedback control is performed using IPD control (integral-proportional integrated control) for each of bounce, pitch, and roll to suppress the vertical acceleration. The control equation for this IPD control is shown in the following equation (2).

(TB3/ (1+TB3・S)) ・K B3+
K B4+ (Ta2・S/(t+TB3・S)) ・K
H2・・・・(2) KH2, KH2, Ta2: Control gain (constant) S: Operator However, in the above equation (2), each control gain is used for bounce control, pitch control, and roll control, respectively. A dedicated one is used.

Since there are only three G-sensors for ride comfort control, the arithmetic mean of the front left and right vertical accelerations is used as the front vertical acceleration for pitch control. In addition, during roll control, only the left and right vertical accelerations on the front side are used, and the vertical accelerations on the rear side are not used.

In this ride comfort control, each control value obtained by the three IPD controls described above is obtained for each of the four cylinder devices 1, and is added to each other for each control value for each cylinder 1, and finally Four flow signals Q for ride comfort control
GFR-QGRL.

■Warp control (pressure signal control) Warp control is a control that suppresses torsion of the vehicle body B. That is, since the pressure acting on each cylinder device 1 corresponds to the load on each wheel, control is performed so that the torsion of the vehicle body B due to this load does not become large.

Specifically, feedback control is performed in a direction such that the ratio of the difference and the sum of left and right pressures is 1 for each of the front side and rear side of the vehicle body. The weighting is such that the amount of torsion on the front side and the rear side of the vehicle body is weighted by a coefficient ωF, and the weighting is applied to each of the above-mentioned controls (1) and (2) by a coefficient ωA. Of course, in this torsion suppression control as well, the control value is finally determined as the flow rate signal QPFR-QPRL (%) for each of the four cylinder devices l. Further, the weighting is such that the difference between the left and right steering characteristics can be changed by changing one or both of the coefficients ωR1ωL.

The flow rate signals for attitude control, ride comfort control, and torsion suppression control determined for each of the four cylinder devices 1 as described above are finally added to form a final flow rate signal QF.
It is determined as R-QRL.

■The control gain of the control formula used in the explanation of FIG. There is. Here, when the vehicle is in a turning state, the damping force switching valve 10 is switched to the throttle position in order to harden the suspension characteristics, and the above-mentioned proportional The constant Ki (i=B+ ``'''B<) is set to a large value K Hard, and the target roll angle T ROLL is set to a large value K Hard.
is set to a value corresponding to the lateral acceleration GS at that time from a map stored in advance. An example of this map is shown in FIG. Incidentally, in the case of a passive suspension vehicle, as shown in FIG. 7, as the lateral acceleration (lateral G) increases, the roll angle (positive roll) increases. Note that the determination of the lateral acceleration Gs (hereinafter referred to as lateral Gs) will be described later.

On the other hand, when the vehicle is traveling straight, in order to soften the suspension characteristics, the damping force switching valve lO is switched to the open position, each of the proportional constants Ki is set to the normal value KSOFT, and the target roll angle is set to the normal value KSOFT. TROLL
Set TROLL=O.

(Hereinafter, blank space) A specific example of 5' roll control will be described based on the flowchart shown in FIG. Incidentally, this FIG. 5 represents control in a transient state. That is, after the steady state is reached, the roll control is performed based on the map shown in FIG. 6 so that the roll angle becomes the target roll angle. That is,
When the lateral Gs is 0.1 or more and 0.3 or less, the roll is reversed, and when the lateral Gs is 0.3 or more, the roll is zero. Can be canceled using the switch).

First, in step Sl (hereinafter, step numbers are indicated by adding rSJ), the traveling direction of the vehicle is determined.

Control when the vehicle is moving forward> When it is determined that the vehicle is moving forward, the process proceeds to S2, where the vehicle speed V is read, and in the next step 33, the steering wheel steering angle θ□ is read, and then in S4, the vehicle speed The lateral Gs is determined from the steering angle of the steering wheel.

Then, by passing through the next 85, S6, and S7, the horizontal G
A region determination of s is performed.

(Lateral Gs<O, i) This region corresponds to rolling of the vehicle due to crosswinds, etc. In this case, the process proceeds from S5 to 88, where the target roll angle TR is set to zero and the displacement speed is set to zero. Here, the displacement speed corresponds to the above-mentioned control gain, and when the displacement speed is small, the suspension characteristics become soft and the characteristics emphasize riding comfort. On the other hand, when the displacement speed is high, the suspension characteristics become hard, suppressing changes in the vehicle's attitude, and giving priority to steering stability. Therefore, in this region, the suspension characteristics emphasize ride comfort.

(0,1≦Lateral Gs<0.3) This region corresponds to normal turning. In this case, the process proceeds from S6 to 89, where it is determined whether or not the mode switch is set to select the reverse roll mode.

When reverse roll mode is canceled, SI
The process advances to O, and the target roll angle is set to zero and the displacement speed is set to 0.03. That is, the suspension characteristics tend to be hard, and changes in the posture of the vehicle are suppressed.

On the other hand, when the reverse roll mode is selected, S
Proceeding to ll, the target roll angle is set to TR=reverse roll 10, and the displacement speed is set to 0.01. Here, TR=
Reverse roll lO means that the difference between the vehicle height on the inner wheel side of the turn and the vehicle height on the outer wheel side of the turn is 10 mm, and of course the vehicle height of the inner wheel side of the turn is lower than the vehicle height of the outer wheel side of the turn. Ru.

Also, the reason why the displacement speed is set to a small value such as 0.01 is to increase the responsiveness to reverse roll.If the displacement speed (control gain) is set to a large value, reverse roll control will be suppressed. This is because it will happen.

(0,3≦Lateral Gs<0.5) This area is a sharp turning area. In this case, S7 to S
IK progresses, the target roll angle is set to TR = reverse roll 5,
The displacement rate is set to 0.05. In other words, in a steady turn in this region, the roll angle is zero, as shown in Figure 6, but in the transition region to a steady turn, the roll angle is reversed, and the transition to a steady turn is smooth. It is designed to be Further, the reason why the displacement speed is set to a large value of 0.05 is to suppress attitude changes and ensure steering stability.

(0,5≦Lateral Gs) This region appears during a transition, and this TR=reverse roll 3 is set, and the displacement speed is set to 0.07. Here, the reason why the target roll angle is set as a reverse roll is that the displacement speed is set to an extremely large value of 0.07. In other words, a large control gain is set in order to suppress posture changes, but since this displacement speed exceeds the maximum flow rate in the example, by setting the target roll angle to reverse roll, centrifugal It is possible to suppress the occurrence of large positive rolls due to force.

Control when moving backward> The angle is set to zero and the displacement speed is set to 0.03. That is,
The suspension characteristics when reversing are different from the suspension characteristics during forward movement described above, and when reversing, both forward roll and reverse roll are prohibited, and the displacement speed is set to a relatively large value of 0.03. This is designed to suppress changes in the vehicle's attitude. As a result, changes in the driver's line of sight are suppressed when reversing, and steering stability when reversing is ensured.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and is a diagram showing a hydraulic fluid circuit. FIG. 2 is a sectional view showing an example of the pilot valve in FIG. 1. FIG. 3 is a diagram showing a control system of the circuit shown in FIG. 1. FIG. 4 is a diagram showing an example for performing active control. FIG. 5 is a flowchart showing an example of control. FIG. 6 is a diagram showing an example of roll characteristics in an active suspension vehicle. FIG. 7 is a diagram showing an example of roll characteristics in a passive suspension vehicle. FIG. 8 is an overall configuration diagram of the present invention. U: IFR~IRL: 5: l 1: 12: 15FR~15RL 19FR~l 9RL 52FR~52RL 53FR~53RL Control unit Cylinder device Liquid chamber Pump reservoir tank: Supply control valve: Discharge control valve: Sensor (pressure) : Sensor (vehicle height) 0 9 Fig. 6 Fig. 7 Area G Fig.

Claims (1)

[Claims] (1) In a vehicle suspension system in which a cylinder device is installed between a sprung mass and an unsprung mass, and the supply and discharge of hydraulic fluid to the cylinder device is controlled based on preset conditions. , a traveling direction determining means for determining whether the vehicle is moving forward or backward, and a characteristic that receives a signal from the traveling direction determining means and switches to a forward suspension characteristic when the vehicle is moving forward, and to a reverse suspension characteristic when the vehicle is reversing. A suspension device for a vehicle, comprising: a changing means;